Review on [2-Pack] LEICESTERCN 12V Battery Trickle Charger Maintainer - Portable Smart Float Charger for Car, Motorcycle, Lawn Mower - SLA, AGM, Gel, Wet, Lead Acid Batteries by Rick Ross

I use this as a replacement for the 12v power supply on my front door opener. About once a year lightning strikes and burns out the charging circuitry, but if I replace the board it's about $150. So I experimented with this block: bypassed the board and connected this block instead. It works great! Even though everything is surge protected, I still have to replace this unit about once a year. but $20 is way better than $150!